JP2015174320A - Manufacturing method of woody composite material, and aqueous adhesive composition used for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a woody composite material which has a superior adhesive strength even when a pressure clamping time is short, and to provide an aqueous adhesive composition used for the manufacturing method of the woody composite material.SOLUTION: In a manufacturing method of a woody composite material made by adhering a plurality of woody materials by using an aqueous adhesive composition, the plurality of woody materials are sawn board or square timber, one side surface of one side woody material is heated, thereby, a contact angle of the heated surface to water is lowered to 97% or less of a contact angle before heating, thereafter, the aqueous adhesive composition is applied on the heated surface of the one side woody material within a time of the range of 60 min immediately after heating completion and, onto the coated surface, other side woody material uncoated with the aqueous adhesive composition or other side woody material which is precoated with the aqueous adhesive composition is stuck to be integrated.

Description

  The present invention relates to a method for producing a wood composite material and an aqueous adhesive composition used therefor.

  A wood composite material used for residential building materials, home interior materials, furniture, etc., which is made by adhering a ground plate or square wood, and a material obtained by adhering a medium density fiberboard (hereinafter abbreviated as MDF) and plywood. Etc. are known.

  2. Description of the Related Art Conventionally, as a method for producing a wood composite material composed of a plurality of saws or squares, a method of bonding using an aqueous adhesive composition containing a main agent made of an emulsion containing an aqueous polymer is known.

  On the other hand, as a method for producing a wood composite material composed of MDF and plywood, one side of a wood material composed of MDF is heated at a temperature of 105 ° C. for 30 seconds to dry the surface, and immediately, a solid content as an aqueous adhesive is applied to the dry surface. There is known a method in which an application surface of a plate material made of a plywood coated with an aqueous adhesive composition containing 49% vinyl acetate emulsion is adhered and adhered (see, for example, Patent Document 1).

JP 2012-206452 A

  However, the wood composite material composed of a plurality of ground plates or squares obtained by the above manufacturing method has a disadvantage that it is necessary to make the wood materials adhere to each other for a long time and is excellent even immediately after bonding. It is desirable to have adhesive strength.

  An object of this invention is to provide the manufacturing method of the wood composite which can obtain the outstanding adhesive strength even if the pressing time is short, and the aqueous adhesive composition used therefor.

  In order to achieve this object, a method for producing a wood composite material of the present invention is a method for producing a wood composite material in which a plurality of wood materials are bonded using an aqueous adhesive composition, wherein the plurality of wood materials are In the range of 60 minutes from the end of heating, after making the contact angle of water on the heating surface to 97% or less before heating by heating one side of one woody material In time, the aqueous adhesive composition is applied onto the heating surface of the one wooden material, and the other wooden material to which the aqueous adhesive composition has not been applied or the other previously applied wooden material is applied to the application surface. It is characterized by being integrated together.

  In the present invention, a wooden board or square is used as the wooden material. First, one wooden material is heated so that the contact angle with respect to water on the heating surface is reduced to 97% or less before heating. Thereby, the heating surface of said one woody material will be in the state which the water | moisture content in the aqueous adhesive composition apply | coated after that easily diffuses inside.

  Next, at a time in the range of 60 minutes immediately after the end of heating, the aqueous adhesive composition is applied on the heated surface of the one wooden material, and the other non-coated aqueous adhesive composition is applied on the applied surface. Laminate and integrate wood materials. Alternatively, during the time period in the range of 60 minutes immediately after the end of the heating, the other aqueous adhesive composition is applied to the heated surface of the one wooden material and the aqueous adhesive composition is applied to the applied surface in advance. Laminate and apply the wood material application surface.

  As described above, it is possible to obtain a wood composite material in which a plurality of ground plates or square members are bonded.

  The resulting wood composite made by bonding a plurality of saws or squares is superior in adhesion even when the pressing time is short compared to the wood composite obtained by the conventional manufacturing method that does not heat at all. Strength can be obtained.

  When the contact angle of the heating surface is not reduced to 97% or less before heating, moisture in the aqueous adhesive composition applied thereafter is diffused on the heating surface of the one wooden material. It cannot be made easy to do.

  Further, if the time from the end of heating to the application exceeds 60 minutes, excellent adhesive strength cannot be obtained even if the pressing time is short.

  The reason why the wood composite material having excellent adhesive strength can be obtained even when the pressing time is short is considered to be due to the following reason.

  The saw board and the square are materials obtained by cutting a log-like wood with a saw. Therefore, the ground board and the square lumber exist on the surface without destruction of the cells of the wood, and moisture tends to hardly diffuse inside other than the conduit and the temporary conduit. For this reason, when bonding a sawing board and a square with the water-based adhesive composition, moisture contained in the aqueous adhesive composition is difficult to diffuse into the inside of the sawing board and the square, and excellent in a short pressing time. The adhesive strength cannot be obtained.

  On the other hand, in this invention, before adhering the several woody material which consists of a grinding board or a square material using an aqueous adhesive composition, one woody material is heated. At this time, due to the heating, the heating surface of the sawing board or the square is changed and the water easily diffuses, and accordingly, the contact angle of the heating surface with respect to water is reduced to 97% or less before the heating. become. As a result, when a wood composite material is formed by pasting and integrating the other wood material on the heating surface of the one wood material via an aqueous adhesive composition within a time period of 60 minutes immediately after the end of heating. Moreover, it is considered that excellent adhesive strength can be obtained even if the pressing time is short. However, when it exceeds 60 minutes from the end of heating, the effect cannot be obtained even if the contact angle with respect to water on the heating surface is lower than that before heating, although the mechanism is unknown.

  Moreover, in the manufacturing method of the woody composite material of this invention, it is preferable that the time from the said heating end to the said application | coating is the time of the range for 1 to 60 minutes. After 1 minute or more has elapsed from the end of heating, by applying the aqueous adhesive composition on the heating surface of the one woody material, the surface temperature of the heating surface can be lowered to around room temperature, Good adhesion can be achieved without impairing the performance of the aqueous adhesive composition itself.

  When the time from the end of heating to the application is less than 1 minute, the surface temperature of the heating surface may be too high. In this case, the water-based adhesive composition itself is heated and dried, resulting in dry adhesion and poor adhesion, or deficiency due to excessive penetration of the water-based adhesive composition into the wood material. If the one woody material and the other grinding board are bonded together in a state where the heating surface is expanded, warping may occur later.

  The manufacturing method of the wood composite material of this invention can be performed suitably about the ground board or square material which consists of conifers.

  Further, in the method for producing a wood composite material of the present invention, an aqueous adhesive composition containing a main agent composed of an emulsion containing an aqueous polymer can be suitably used. Further, the aqueous adhesive composition is made of an isocyanate compound. A curing agent may be included.

  Next, embodiments of the present invention will be described in more detail.

  The method for producing a wood composite material according to the present embodiment is a wood board or a square material (hereinafter abbreviated as a wood board) as a wood material in order to produce a wood composite material used for a housing building material, a house interior material, furniture, or the like. ) Using an aqueous adhesive composition. The production method can be applied to all kinds of wood, but is particularly suitable for conifers such as cedar, cypress, bay pine, larch, Scots pine, and spruce.

  In the manufacturing method of this embodiment, before bonding a plurality of grinding boards using an aqueous adhesive composition, by heating one of the grinding boards, the contact angle with respect to the water of the heating surface is 97% or less before heating. To a lowered state. The heating can be performed, for example, by irradiating a ground plate with near infrared rays, bringing a hot plate into close contact, supplying warm air, or heating with a heater.

  After the heating, the heating surface of the one grinding board is in a state where the contact angle with respect to water is reduced to 97% or less before the heating, and the moisture is easily diffused into the inside of the grinding board.

  Then, immediately after the heating of the one grinding board is finished, preferably at a time in the range of 1 minute to 60 minutes, the aqueous adhesive composition is applied onto the heating surface of the one grinding board.

  Then, immediately after the application, the other grinding board is adhered and adhered to the application surface of the one grinding board, and the wooden composite material in which the two grinding boards are bonded together by pressing and integrating them. Can be obtained.

  The obtained wood composite material can obtain excellent adhesive strength even if the pressing time is short, compared with the conventional production method, that is, the wood composite material bonded without any heating itself. .

  In the heating, only one of the grinding boards may be heated, or both of the grinding boards may be heated. In the case of heating both grinding boards, the adhesive composition is applied to the heating surface of one grinding board, and then the heating surface of the other grinding board is bonded to the application surface.

  The other grinding board to be bonded to the application surface of the one grinding board may be uncoated with the aqueous adhesive composition, or may be applied in advance. When the other ground plate to which the water-based adhesive composition is applied in advance is bonded to the one ground plate, the application surfaces of the respective ground plates are bonded to each other.

  Next, the aqueous adhesive composition used in the production method of this embodiment will be described.

  As the aqueous adhesive composition, a composition containing a main agent composed of an emulsion containing an aqueous polymer can be used. The aqueous adhesive composition may further contain a curing agent composed of an isocyanate compound. In this case, the isocyanate compound is in the range of 2 to 40% by mass, preferably 5 to 30%, based on the total amount of the aqueous polymer. Including in the range of mass%.

  The main component of the aqueous adhesive composition includes, as an emulsion containing the aqueous polymer, at least one solution selected from the group consisting of an aqueous water-soluble polymer aqueous solution, an aqueous emulsion, and an aqueous latex, and further includes a filler, A dispersant for the filler may be included.

  Examples of the water-soluble polymer include polyvinyl alcohol, acetoacetylated polyvinyl alcohol, aminated polyvinyl alcohol, carboxylated polyvinyl alcohol, cationized polyvinyl alcohol, anionized polyvinyl alcohol, starch, protein, carboxymethylcellulose, and hydroxyethylcellulose. Examples thereof include cellulose derivatives, polyacrylic acid soda, polyacrylamide, and maleic acid imide copolymers. The water-soluble polymer may be used as an aqueous solution.

  Examples of the aqueous emulsion or aqueous latex include styrene, butadiene, acrylamide, acrylonitrile, chloroprene, 1,3-hexadiene, isoprene, isobutene, acrylic ester, methacrylic ester, vinyl acetate, vinyl propionate, ethylene, vinyl chloride. An aqueous latex or aqueous emulsion of one compound selected from the group consisting of vinylidene chloride and ethyl vinyl ether, or an aqueous latex consisting of two or more copolymerizable unsaturated monomers selected from the group Mention may be made of aqueous emulsions.

  The aqueous latex or aqueous emulsion is at least selected from the group consisting of carboxyl group, N-methylol group, N-alkoxymethyl group, glycidyl group, β-methylglycidyl group, hydroxyl group, amino group, amide group, and acid anhydride. A modified latex or modified emulsion obtained by emulsion polymerization of an unsaturated monomer having one kind of reactive group may be used. The aqueous latex or aqueous emulsion may be a solid that easily becomes an aqueous latex or aqueous emulsion by adding and stirring in water.

  Examples of the filler include organic fillers such as wheat flour, soybean flour, blood flour, wood flour, and walnut shell flour, and inorganic fillers such as clay, kaolin, zeolite, calcium carbonate, talc, silica, aluminum oxide, and titanium oxide. A filler etc. can be mentioned. Any one of these fillers can be used alone, or two or more of them can be used in combination.

  Examples of the dispersant for the filler include inorganic dispersants such as sodium metaphosphate and ammonium dihydrogen phosphate, and polymer dispersants such as sodium dodecylbenzenesulfonate. Any one of the filler dispersants may be used alone, or two or more of them may be used in combination.

  Examples of the isocyanate compound used for the curing agent of the aqueous adhesive composition include hexamethylene diisocyanate, isophorone diisocyanate (IPDI), phenylene diisocyanate, cyclohexyl diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, hydrogenated xylylene diisocyanate, and water. Trimethylxylylene diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate, 2,2,4-trimethylhexamethylene-1,6-diisocyanate, 2,4,4- Trimethylhexamethylene-1,6-diisocyanate, 4,4-dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, paraphenylene diisocyanate, 2,4-triisocyanate Diisocyanate, 2,6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, tetramethylxylylene diisocyanate, 4,4-diphenyl ether diisocyanate, 2,2'-diphenylmethane diisocyanate 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,3-xylylene diisocyanate and 1,4-xylylene diisocyanate Mixtures, polymethylene polyphenyl polyisocyanates, etc., and dimers, trimers, burettes, carbon dioxide gas derived from polymethylene polyphenyl polyisocyanate monomers It may be mentioned polyisocyanates having 2,4,6 oxaziridine trione ring obtained from the re polyphenyl polyisocyanate monomer.

  The isocyanate compound may be an ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, cyclohexane dimethanol or other low molecular weight polyol, an adduct of a carbodiimide compound and a polyisocyanate, or a polyester polyol or a polyether polyol. NCO terminal compounds such as an adduct of a polymer polyol of polyisocyanate and the like, and a mixture of two or more thereof may be used.

  The aqueous adhesive composition further includes a curing agent, a dispersant, an antifoaming agent, an antiseptic, an antifungal agent, an antifungal agent, an antifoaming agent, a foam stabilizer, a foaming agent, within a range that does not impair the adhesive performance Additives such as a fireproofing agent, a rustproofing agent, a wetting agent, a wettability modifier, a film forming aid, and a viscosity modifier may be included.

  Moreover, in the manufacturing method of the wood composite material of this embodiment, the hardening containing polyvinyl alcohol, the ethylene-vinyl acetate copolymer emulsion, the main ingredient containing styrene butadiene latex, and the modified product of polymethylene polyphenyl polyisocyanate. An aqueous adhesive composition containing an agent can be particularly preferably used.

  Next, an Example and a comparative example are shown about the manufacturing method of the woody composite material of this invention.

[Experiment 1] (Example 1-4 and Comparative Example 1-4)
First, an experiment was conducted by varying the time required from the end of heating to the application of the aqueous adhesive composition.

[(1) Preparation of aqueous adhesive composition]
As an aqueous adhesive composition, an aqueous adhesive composition A prepared by preparing and pasting 100 parts by mass of a main agent composed of an emulsion containing an aqueous polymer and 15 parts by mass of a curing agent composed of an isocyanate compound at a temperature of 5 ° C. Prepared.

  As the main ingredients, polyvinyl alcohol (trade name: Kuraray Poval PVA-217, Kuraray Co., Ltd.) 15 parts by weight as a water-soluble polymer aqueous solution, 15 parts by weight, ethylene-vinyl acetate copolymer emulsion (product) as an aqueous emulsion Name: Sumikaflex 400HQ, Sumitomo Chemical Co., Ltd. 30 parts by mass, styrene butadiene latex (trade name: DL-612, Asahi Kasei Chemicals Co., Ltd.) 10 parts by mass as aqueous latex, and calcium carbonate (trade name: filler) Prepared by mixing 35 parts by weight of Whiten P-30, Toyo Fine Chemical Co., Ltd.), 0.5 parts by weight of sodium hexametaphosphate as a dispersant for the filler, and 10 parts by weight of water as a viscosity modifier. What was done was used.

  A modified product of polymethylene polyphenyl polyisocyanate (trade name: SBU isocyanate J243, Sumika Bayer Urethane Co., Ltd.) was used as the curing agent.

[(2) Creation of wood composite board]
As the wood material, four cedar grinding boards (referred to as cedar grinding boards A, B, C, and D) having a bonding area of 40 mm in length, 40 mm in width, and 30 mm in thickness were prepared. The cedar board had a water content of 6 to 12% and a specific gravity of 0.4 to 0.5 at a temperature of 5 ° C.

  First, one side of the cedar ground board A was heated by irradiating the single side of the cedar ground board A at a temperature of 5 ° C. for 10 seconds from a position 50 mm away. The near-infrared irradiation uses a near-infrared irradiation device (trade name: near-infrared dryer quick layer SQR600W, Daito Sangyo Co., Ltd.), and a near-infrared wavelength of 0.8 to 1.2 μm at a voltage of 200 V and a power of 2 kW. Performed by irradiation.

Next, immediately after the completion of heating, 250 g / m ² of the aqueous adhesive composition A was applied to the heated surface of the cedar ground board A. Then, after 1 minute of the open deposition time, the cedar grinding board B which has not been heated or coated with the aqueous adhesive composition A is pasted and adhered to the heated surface of the cedar grinding board A, and after 10 minutes of the closed deposition time. Clamping was performed at a pressure of 1.2 MPa for 20 or 25 minutes. Then, by releasing the pressure after completion of the pressing, a wood composite material was prepared by integrating the cedar ground plates A and B (Example 1).

  Further, the time from the end of heating to the application of the aqueous adhesive composition is 10 minutes (Example 2), 30 minutes (Example 3), 60 minutes (Example 4), 90 minutes (Comparative Example 1), 120 minutes. A wood composite was prepared in exactly the same manner as in Example 1 except that (Comparative Example 2) or 180 minutes (Comparative Example 3).

  Further, a wood composite material was prepared in exactly the same manner as in Example 1 except that no heating was performed before applying the aqueous adhesive composition (Comparative Example 4).

[(3) Measurement of splitting strength]
With respect to the obtained wood composite material, immediately after the decompression, the splitting strength was measured in accordance with the splitting adhesive strength test method of the adhesive specified in JISK6853. In the test, the moving speed of the crosshead was 2 mm / min.

[(4) Temperature measurement of heated surface of cedar grinding board]
Next, the cedar grinding board C was heated under the same conditions, and the temperature change of the heating surface was measured to examine the temperature change of the heating surface of the cedar grinding board A after the start of heating. Among the measured temperatures, the highest temperature was defined as the temperature reached by the heating surface.

[(5) Measurement of contact angle]
Next, after performing the said heating on the same condition about the 4th sawing board, ion-exchange water is dripped and using a contact angle meter (CA-X type, Kyowa Interface Chemical Co., Ltd.), The contact angle of the heated surface of the cedar ground plate A was determined by measuring the contact angle with water (hereinafter sometimes abbreviated as “contact angle”).

[(6) Result]
Table 1 shows the splitting strength at the pressing time of 20 minutes and 25 minutes, the ultimate temperature of the heated surface of the cedar ground plate, the contact angle of the heated surface with water, and the rate of change of the contact angle before and after heating. The rate of change of the contact angle indicates a percentage of the contact angle of a cedar ground board (Comparative Example 4) that has not been heated at all. Table 2 shows the temperature change of the heating surface of the cedar ground board A.

[Experiment 2] (Example 5-10)
Next, an experiment was performed by changing the temperature reached by the heating surface of the cedar ground board A by changing the irradiation conditions of the near infrared rays.

  First, except that the heating was performed by irradiating near infrared rays from a position 50 mm away from the cedar grinding board A for 2 seconds (Example 5) or 5 seconds (Example 6), it was exactly the same as Example 1. A wood composite was created.

  Further, except that the heating was performed by irradiating near infrared rays from a position 100 mm away from the cedar grinding board A for 5 seconds (Example 7) or 10 seconds (Example 8), it was exactly the same as Example 1. A wood composite was created.

  Further, a wood composite material was prepared in exactly the same manner as in Example 1 except that the heating was performed by irradiating near infrared rays from a position 200 mm away from the cedar grinding board A for 5 seconds (Example 9).

  Further, a wood composite material was prepared in exactly the same manner as in Example 1 except that the heating was performed by irradiating near infrared rays from a position 500 mm away from the cedar grinding board A for 60 seconds (Example 10).

  Next, for each of the obtained wood composite materials, the splitting strength at the pressing time of 20 minutes and 25 minutes, the ultimate temperature of the heating surface of the cedar grinding plate, and the contact angle were measured. The results are shown in Table 1.

[Experiment 3] (Examples 11-24 and Comparative Example 5-7)
Next, the experiment was performed by changing the heating means to a hot plate or hot air.

  First, in place of heating by near-infrared irradiation, except that heating was performed by bringing the cedar ground plate A into contact with a hot plate of a hot press (Hiroko Engineering Co., Ltd.) heated to a surface temperature of 100 ° C. for 10 seconds. A wood composite was prepared exactly as in Example 1 (Example 11). The time from the end of heating to the application of the aqueous adhesive composition was 1 minute.

  Next, the time from the end of heating to the application of the aqueous adhesive composition was 10 minutes (Example 12), 30 minutes, (Example 13), 60 minutes (Example 14), 90 minutes (Comparative Example 5), A wood composite was prepared in exactly the same manner as in Example 11 except that the time was 120 minutes (Comparative Example 6) or 180 minutes (Comparative Example 7).

  Next, an experiment was conducted by changing the temperature reached by the heating surface of the cedar ground plate A by changing the heating conditions by the hot plate.

  First, in the heating, the cedar grinding board A is placed on the hot plate heated to a surface temperature of 100 ° C. for 1 second (Example 15), 2 seconds (Example 16), 5 seconds (Example 17) or 60 seconds ( Example 18) A wood composite was prepared in exactly the same way as in Example 11 except that the contact was made by contacting.

  In addition, Example 11 was performed except that the heating was performed by bringing the cedar ground plate A into contact with the hot plate heated to a surface temperature of 80 ° C. for 1 second (Example 19) or 2 seconds (Example 20). A wood composite was made in exactly the same way.

Next, instead of heating by near-infrared irradiation, heating was performed by supplying hot air at a temperature of 400 ° C. from a position 150 mm away from the cedar grinding board A for 1 second at a flow rate of 0.18 m ³ / min. A wood composite was prepared exactly as in Example 1 (Example 21). The time from the end of heating to the application of the aqueous adhesive composition was 1 minute.

  Next, the wood composite material was exactly the same as Example 21, except that the supply time of the warm air was 2 seconds (Example 22), 5 seconds (Example 23), or 10 seconds (Example 24). It was created.

  Next, for each of the obtained wood composite materials, the splitting strength at the pressing time of 20 minutes and 25 minutes, the ultimate temperature of the heating surface of the cedar grinding plate, and the contact angle were measured. The results are shown in Table 1.

  In Table 1, the wood composite material of Example 1-24 was heated on one side of one grinding board before applying the aqueous adhesive composition, and the contact angle of water on the heating surface with water was 97% or less before heating. In addition, the aqueous adhesive composition was applied for a time in the range of 1 minute to 60 minutes from the end of heating, and the other ground plate was bonded and integrated. On the other hand, the wood composite materials of Comparative Examples 1-3 and 5-7 were coated with an aqueous adhesive composition at a time in the range of 90 minutes to 180 minutes from the end of the heating, and the other grinding board was bonded and integrated. Is. Moreover, the woody composite material of Comparative Example 4 is obtained by applying and integrating the aqueous adhesive composition without performing any heating.

  According to Table 1, the wood composite material of Example 1-24 has a pressing time of 20 minutes or less compared to the wood composite material of Comparative Example 4 and the wood composite material of Comparative Examples 1-3 and 5-7. The splitting strength after 25 minutes is high.

  From this, regardless of the heating means and the ultimate temperature of the heating surface, according to the production method of the wood composite material of Example 1-24, the wood composite material having excellent adhesive strength even with a short pressing time. Can be obtained.

  Moreover, it is clear from Table 2 that the temperature of the heating surface (adhesion surface) of the cedar ground plate A has dropped to a temperature close to the temperature before heating when 1 minute or more has elapsed since the end of heating. Therefore, by applying the aqueous adhesive composition after 1 minute or more has elapsed from the end of heating, it is possible to prevent the effects of drying of the aqueous adhesive composition accompanying the heating, expansion of the adhesive surface of the cedar grinding board A, and the like. It is considered a thing.

[Experiment 4] (Examples 25-33 and Comparative Example 8-10)
Next, an experiment was performed using a ground plate whose tree species is pine, Scots pine or spruce.

  First, a wood composite was prepared in exactly the same manner as in Example 7 except that a pine pine board was used instead of the cedar ground board as the wood material (Example 25). The bay pine ground board had a water content of 8 to 12% and a specific gravity of 0.50 to 0.60 at a temperature of 5 ° C. The bay pine grinding board was heated by irradiating near infrared rays for 5 seconds from a position 100 mm away.

  Further, a wood composite material was prepared in exactly the same manner as in Example 16 except that a bay pine grinding board was used instead of the cedar grinding board as a wood material (Example 26). The pine pine was heated by bringing it into contact with the hot plate heated to a surface temperature of 100 ° C. for 2 seconds.

Further, a wood composite material was prepared in exactly the same manner as in Example 21 except that a bay pine ground board was used instead of the cedar ground board as a wood material (Example 27). The bay pine grinding board was heated by supplying hot air at a temperature of 400 ° C. from a position 150 mm away for 1 second with an air flow of 0.18 m ³ / min.

  Next, a wood composite was prepared in exactly the same manner as in Example 25, Example 26 or Example 27 except that Scots pine slab was used in place of the bay pine saw (Examples 28 and 29). Example 30). The Scots pine ground board had a water content of 8 to 12% and a specific gravity of 0.50 to 0.60 at a temperature of 5 ° C.

  Further, a wood composite material was prepared in exactly the same manner as in Example 25, Example 26 or Example 27 except that spruce grinding board was used instead of bay pine grinding board (Example 31, Example 32, Example). 33). The spruce ground board had a water content of 8 to 12% and a specific gravity of 0.35 to 0.45 at a temperature of 5 ° C.

  Next, a wood composite was prepared in exactly the same manner as in Comparative Example 4 except that instead of the cedar grinding board, a bay pine grinding board, a red pine grinding board, or a spruce grinding board was used as the wooden material (comparison) Example 8, Comparative Example 9, and Comparative Example 10). In Comparative Example 8-Comparative Example 10, the grinding board was not heated at all.

  Next, with respect to each obtained wood composite material, the splitting strength at the pressing time of 20 minutes and 25 minutes, the ultimate temperature of the heated surface of the grinding plate, and the contact angle were measured. The results are shown in Table 3.

[Experiment 5] (Comparative Example 11-16)
Next, an experiment was performed using MDF and plywood as a wood material.

  First, a wood composite was prepared in exactly the same manner as in Example 7 except that MDF was used in place of cedar grinding board A and 12 mm lauan plywood was used in place of cedar grinding board B (Comparative Example 11). MDF is obtained by mixing wood fiber with an adhesive composition made of phenol resin and hot pressing it into a plate shape, with a moisture content of 6-7% and a specific gravity of 0.74-0.77 at a temperature of 5 ° C. there were. The time from the end of heating to the application of the aqueous adhesive composition was 1 minute.

  Next, the time from the end of heating to the application of the aqueous adhesive composition was 10 minutes (Comparative Example 12), 30 minutes, (Comparative Example 13), 60 minutes (Comparative Example 14) or 90 minutes (Comparative Example 15). Except for the above, a wood composite was prepared in exactly the same manner as in Comparative Example 11.

  Next, a wood composite was prepared in exactly the same manner as Comparative Example 4 except that MDF was used instead of the cedar ground board A and 12 mm lauan plywood was used instead of the cedar ground board B (Comparative Example 16). In Comparative Example 16, the grinding board was not heated at all.

  Next, with respect to each obtained wood composite material, the splitting strength at the pressing time of 20 minutes and 25 minutes, the ultimate temperature of the cedar ground plate or the heating surface of the MDF, and the contact angle were measured. The results are shown in Table 3.

  According to Table 3, the wood composites of Examples 25-33 were compared with the wood composites of Comparative Examples 8-10, which were not heated at all, when the pressing time was 20 minutes or 25 minutes, respectively. High splitting strength.

  From this, when the wood material is a ground board regardless of the tree species, one side of one ground board is heated, and the contact angle with respect to the water of the heating surface is reduced to 97% or less before heating. At the same time, by applying the aqueous adhesive composition in the time range from 1 minute to 60 minutes from the end of heating and pasting and integrating the other grinding plate, it has excellent adhesive strength even if the pressing time is short A wood composite can be obtained.

  Moreover, according to Table 3, the contact angle of the wood composite material of Comparative Example 11-15 using MDF and plywood as the wood material is not decreased as compared with the wood composite material of Comparative Example 16. The splitting strength has hardly changed.

  Therefore, when MDF and plywood are used as the wood material, the wood composite having excellent adhesive strength when the pressing time is short even if the MDF is heated before the aqueous adhesive composition is applied. I can't get the material.

[Experiment 6] (Examples 34-38 and Comparative Examples 17-21)
Next, regarding the method for producing a wood composite material of cedar ground board, an experiment was performed using an aqueous adhesive composition different from Experiment 1.

  First, aqueous adhesive compositions B to F were prepared as aqueous adhesive compositions.

  The aqueous adhesive composition B is an aqueous adhesive composition (trade name: Shinko Bond 66K, Oshika Corporation) whose main component is a vinyl acetate resin emulsion.

  The aqueous adhesive composition C is an aqueous adhesive composition (trade name: Sumikaflex 400HQ, Sumitomo Chemical Co., Ltd.) whose main component is an ethylene-vinyl acetate copolymer emulsion.

  The aqueous adhesive composition D is an aqueous adhesive composition (trade name: Polytron T8200A, Asahi Kasei Chemicals Corporation) whose main component is acrylic styrene butadiene latex.

  The aqueous adhesive composition E is an aqueous adhesive composition (trade name: Asahi Kasei Latex SB DL-612, Asahi Kasei Chemicals Co., Ltd.) whose main component is styrene butadiene latex.

  The aqueous adhesive composition F is an aqueous adhesive composition (trade name: Hydran HW-311, DIC Corporation) whose main component is a urethane resin dispersion.

  Note that none of the aqueous adhesive compositions B to F contains a curing agent.

  Next, a wood composite was prepared exactly as in Example 7 or Comparative Example 4 except that the aqueous adhesive compositions B to F were used (Examples 34-38 and Comparative Examples 17-21).

  Next, for each of the obtained wood composite materials, the splitting strength at the pressing time of 20 minutes and 25 minutes, the ultimate temperature of the heating surface of the cedar grinding plate, and the contact angle were measured. The results are shown in Table 4.

  According to Table 4, the wood composite materials of Examples 34-38 were compared with the wood composite materials of Comparative Examples 17-21 that were not heated at all, when the pressing time was 20 minutes or 25 minutes. High splitting strength.

  From this, regardless of the type of water-based adhesive composition, one side of one grinding board is heated so that the contact angle with respect to water on the heating surface is reduced to 97% or less before heating, and heating is performed. One minute after the completion, the aqueous composite composition is applied and the other ground plate is laminated and integrated to obtain a wood composite material having excellent adhesive strength even if the pressing time is short.

[Experiment 7] (Examples 39-41 and Comparative Example 22)
Next, after applying 250 g / m ² of the aqueous adhesive composition A to the heating surface of the cedar grinding board A, the cedar grinding board B which is not heated or applied with the aqueous adhesive composition A is pasted together. Instead of the tightening method, 125 g / m ² of the aqueous adhesive composition A is applied to the heated surface of the cedar grinding board A, while the aqueous adhesive composition A is applied to one side of the cedar grinding board B that is not heated at all. A wood composite was produced in exactly the same manner as in Example 7, Example 16 or Example 21 except that 125 g / m ^{2 was} applied and both coated surfaces were bonded together and pressed (Example 39, Example 40). Example 41).

In Example 39, the cedar grinding board A was heated by irradiating near infrared rays for 5 seconds from a position 100 mm away. In Example 40, the cedar ground plate A was heated by bringing it into contact with the hot plate heated to a surface temperature of 100 ° C. for 2 seconds. In Example 41, the cedar grinding board A was heated by supplying warm air at a temperature of 400 ° C. from a position 150 mm away for 1 second with an air flow of 0.18 m ³ / min.

  Further, a wood composite was prepared in exactly the same manner as in Example 39, except that the cedar grinding board A was not heated at all before applying the aqueous adhesive composition A (Comparative Example 22).

  Next, with respect to each obtained wood composite material, the splitting strength at the pressing time of 20 minutes and 25 minutes, the ultimate temperature of the heated surface of the grinding plate, and the contact angle were measured. The results are shown in Table 5.

  According to Table 5, the wood composite board of Examples 39-41 has a higher splitting strength when the pressing time of 20 minutes or 25 minutes has elapsed than the wood composite material of Comparative Example 22.

  From this, even when applying the aqueous adhesive composition to both cedar grinding boards A and B, according to the production method of the wood composite material of Examples 39-41, it is excellent even in a short pressing time. A wood composite material having high adhesive strength can be obtained.

Claims (5)

A method for producing a wood composite material in which a plurality of wood materials are bonded using an aqueous adhesive composition,
The plurality of wood materials are sawn timber or square wood,
One side of the wood material is heated so that the contact angle with respect to water of the heating surface is reduced to 97% or less before the heating, and then the one wood material is within a period of 60 minutes immediately after the end of heating. The aqueous adhesive composition is applied onto the heating surface of the substrate, and the other adhesive is applied to the other surface of the wooden material to which the aqueous adhesive composition has not been applied or the other wooden material previously applied. A method for producing a characteristic wood composite.   The method for producing a wood composite material according to claim 1, wherein the time from the end of heating to the application is in the range of 1 to 60 minutes.   The method for producing a woody composite material according to claim 1 or 2, wherein the sawboard or square wood is made of coniferous wood. A water-based adhesive composition used in the method for producing a wood composite according to any one of claims 1 to 3,
An aqueous adhesive composition comprising a main agent comprising an emulsion containing an aqueous polymer.   The aqueous adhesive composition according to claim 4, wherein the aqueous adhesive composition contains a curing agent made of an isocyanate compound.